I really like this implemantation but am querry about why I can build on all my planets same wonder. As only one can be build, what happens to the losers? Either in my Empire and other nations that come second. If there is a kind of bonus for half finnished then it can become a game exploit if I can multi build wonders, I think.

You get a development bonus for a wonder on top of your current development from other sources. Note that only the best development bonus from wonders is used on a world, so building a second wonder may not be the best thing. It can still be useful for the wonders other benefits though.

Obviously the HomeWorld has the SPEED which means everything on Wonder building, so forget the Development bonus, it is not worth the risk of not getting the other bonus (the Research ones are the best). But there is an exploit,, well, sort of an exploit.

Go into the Diplomacy screen and click on the Trade thing and the Techs that you have that the AI needs show up. Use this to see if the other AI Races have the Tech required to build the Wonder. If they do not, well.., you can MAYBE build the Wonder in a "slower" (non Home world) colony. But if you are further along and you see that the best AI is two Techs behind the Wonder Tech, well heck, you can build it in SLOWER (non-HomeWorld) colony.

Based on experience, if you pick a very slow colony, the Wonder will take forever to build, so even if you are ahead 2 Techs, do not get too cocky and put it in a super slow colony or the AI could steal it from you by building it first.